Personally I'd use WW1 figures for the Marines, Battle Dress and the later webbing were in short supply even in early 1940. But then I'd argue against Battle Dress in 1938 full stop.

The Navy Officer's (and Petty Officer's) uniform was totally different to earlier times and almost the same as the modern day one.

However Navy Blue battledress was issued during the war, often worn with a white polo neck jumper, or white shirt and black tie, if you aren't too particular. Duffle coats (beige-y brown) were also worn, as were greatcoats (Navy Blue), but I'd expect to see the ratings wearing those if the officer was.
I'd be tempted to use a WW1 British officer and shave off the patch pockets on his tunic. Hopefully no one will notice it's single breasted and not double.